Synergetic effect of titanium dioxide ultralong nanofibers and activated carbon fibers on adsorption and photodegradation of toluene

- We firstly prepare TiO2 nanofiber/activated carbon fiber porous composites.
- TiO2 ultralong nanofibers were constructed by nanocrystals.
- The composites exhibit synergetic adsorption-photocatalytic activities for toluene.
- The adsorption efficiency reaches 98.9% at toluene concentration of <4600 ppm.
- Activated carbon fibers improve the quantum efficiency of TiO2.

Effective adsorption and photodegradation of volatile organic compounds (VOCs) especially for the high concentrations still remained great challenges. Herein, we firstly fabricated ultralong TiO2 nanofiber/activated carbon fiber (TiNF/ACF) porous composites by deposition of TiNFs within ACF felts. The ultralong TiNFs with diameters of 30-100 nm and lengths of >200 μm were originated from the ordered aggregates of nanocrystals along the [1 0 1] direction. The TiNF/ACF porous composites possessed excellent adsorption property for toluene, and the adsorption performances were fit well with pseudo-second-order kinetics model. Their adsorption efficiency reached 98.9% at the toluene concentration of <4600 ppm and 85.7% even at the high concentration of 13,800 ppm. Moreover, the synergetic effect between the TiNFs and ACFs improved remarkably the photodegradation activity of the composites. The ACFs not only increased the quantum efficiency of TiO2 by hindering the recombination of electron-hole pairs, but also enhanced the light adsorption ability by reducing the TiO2 band gap energy (Eg) to 2.99 eV. At the toluene concentrations of 115 ppm or 230 ppm, the photocatalytic time in which toluene degraded into CO2 and H2O was only 5 h or 13 h, respectively. The photodegradation kinetics of toluene matched well with the apparent first-order reaction kinetics model at high concentration of 690 ppm, while that matched well with the semi-empirical power-law expression equation of CO2 desorption at low concentrations of 115 ppm. Hence, the TiNF/ACF porous composites with excellent adsorption and photocatalytic activities had great application potentials for VOC removal.

225